Duplicate numbers recognition

[Guest]

I have a form that enters a number into my table. I want the database to tell
me if the number I am entering is a duplicate. Right now if I duplicate the
number it will let me continue but it does not save the latest information.

 

[Jeff Boyce]

Scott

Instead of using a textbox, requiring the user to remember/enter a
code/number, then refusing to accept the record because it is a duplicate,
it would be a lot more user-friendly to use a combobox that lists all
"current" values. Then you can set the combobox's LimitToList property and
use the NotInList event to add new items...

Regards

Jeff Boyce
Microsoft Office/Access MVP

 

[Guest]

In the Before Update event of the control on the form where the number is
entered, use a DLookup to see if the number in the control exists in the
table and cancel the update if it is:

Private Sub txtTheNumber_BeforeUpdate(Cancel As Integer)

If Not IsNull(DLookup("[TheNumber]", "TheTable")) Then
MsgBox "This Number Already Exists in the Table"
Cancel = True
End If
End Sub